Since a liquid crystal display (LCD) device has advantages of light weight, thin thickness and low power consumption, such an LDC device has been widely used for information handling equipment, such as personal computers and word processors, and video equipment, such as television receivers and car navigation systems, as a display device. Many LCD devices applied to those applications include an illumination unit that projects light from a rear side of a display panel to achieve a bright display picture.
Here, an illumination unit is classified into an edge light system or a directly-under-disposed system depending on its disposition of a light source. The edge light system, for example, includes its light source disposed at an edge of a light guide plate provided opposite to a display panel. The directly-under-disposed system, however, includes a plurality of straight-line light sources of fluorescent discharge tubes or the like provided behind a display panel and a diffusing plate provided between the display panel and the light sources.
It is easily achievable to make the directly-under-disposed system highly brighter than the edge light system. The former is advantageous because a light emitting surface of the former is more uniform in brightness than that of the latter. Recently, larger size LCD devices have been widely used for TV receivers and much brighter LCD devices are required for them. It is essential to adopt a directly-under-disposed type illumination unit for such demands.
Conventionally the structure disclosed in Japanese Patent Publication No. 2003-5157, for instance, is known as a directly-under-disposed type illumination unit. In the LCD device disclosed in Japanese Patent Publication No. 2003-5157, the illumination unit to project light from the rear side of an LCD panel includes a housing, a light source (lamp), a lamp holder to support the light source, a reflective sheet, an optical diffusing plate to efficiently transfer light projected from the light source to the LCD panel, a resin frame and a rear cover containing the light source, the lamp holder, the reflective sheet and the diffusing plate.
When the illumination unit is incorporated into the LCD device, the resin frame is assembled with the rear cover to contain the light source, the reflective sheet, the diffusing plate or the like. In this case, projecting stoppers formed at circumferential portions of the resin frame are inserted into apertures made at their corresponding portions of the rear cover so that the outer circumference of the resin frame is fixed with the inner circumference of the rear cover.
Such assembly of the resin frame with the rear cover, i.e., screw-less fixity, is useful for 20-inch LCD panels of LCD devices or the like. Since, however, LCD devices such as LCD TV receivers have recently become larger in size, the assembly set forth above is difficult to sufficiently fix them together. More concretely, such engaged components provided for those larger LCD devices are insufficient in strength so that falling shocks of the LCD devices or the like, if applied, may cause problematic disassembly of the engaged components.